The semiconductor industry is rapidly decreasing the dimensions and increasing the density of circuitry and electronic components in silicon chips and integrated circuits. In addition, integrated circuits are being layered or stacked with ever decreasing insulating layer thickness between each circuitry layer.
With these decreasing geometries and device sizes, the semiconductor industry has sought to avoid parasitic capacitance and crosstalk noise caused by inadequate insulating layers in the integrated circuits. As operation frequencies approach the GHz regime, low RC (resistance x capacitance) delay constants become essential. One way to achieve the desired low RC delay constants involves use of dielectric material in insulating layers that have a low dielectric constant.
T. Homma, et al., J. Electrochem. Soc., 3/93, vol. 140, No. 3, pp.687-92, discloses the room temperature chemical vapor deposition of SiOF films for interlayers in submicron multilevel interconnections. The technique uses
T. Homma, et al., J. Electrochem. Soc., 1993, Vol. 140, fluorotriethoxysilane and water vapor as source materials. No. 12, pp. 3599-603, discloses the characteristics of SiOF films from various alkoxysilane precursors for interlayer dielectrics in multilevel interconnections.
The articles by T. Homma, et al. have attempted to deposit SiOF from various alkoxyfluorosilanes under an atmospheric pressure chemical vapor deposition process with water as a catalyst. The atomic fluorine percentage is limited in these precursors and volatility of the sources is very low. Films obtained by this process have poor uniformity and contain water.
T. Usami, et al., Jpn. J. Appl. Phys., Part 1, 1993, vol. 33, No. 1B, pp 408-12, report an interlayer dielectric film using fluorine-doped silicon oxide for multilevel interconnection of very large scale integration (VLSI). The film is deposited from hexafluoroethane and tetraethoxysilane using plasma-enhanced chemical vapor deposition. Low dielectric constants are reported to be caused by the Si-F bond formation and SiOF films are reported to have very high applicability as an interlayer dielectric film for advanced VLSI devices. Usami, et al. have deposited SiOF using tetraethoxysilane and hexafluoroethane. Here, more than one source is required to obtain the desired SiOF films, and the vapor pressure of tetraethoxysilane is low.
C. Falcony, et al., Thin Solid Films, 4/91, vol. 199, No. 2, pp269-78, describes the deposition of silicon dioxide films by plasma-enhanced chemical vapor deposition using SiCl.sub.4 and SiF.sub.4.
C. Falcony, et al., J. Vac. Sci. Technol. A, Vac. Surf. Films, 11/93, vol. 11, no. 6, pp. 2945-9, discloses high quality silicon dioxide films deposited by plasma-enhanced chemical vapor deposition using SiF.sub.4 and N.sub.2 O. Hydrogen is used to decrease the amount of residual F in the oxide.
Falcony, et al. have used silicon tetrafluoride as a precursor. Silicon tetrafluoride is a highly toxic compressed gas and is hazardous to handle.
U.S. Pat. No. 5,268,202 describes the deposition of low dielectric interlayers for electronic devices and modules using fluorinated parylene.
S. E. Johnson, et al., Inorganic Chemistry, 1989, Vol. 28, No. 16, p. 3183(h), discloses the synthesis of F.sub.3 SiCH.sub.2 CH.sub.2 CH.sub.2 SiF.sub.3.
M. Voronkov, et al., J. Organomet. Chem. 1990, 389(1), PP 1-22, discloses the compositions: FMe.sub.2 SiCH.sub.2 CH.sub.2 SiMe.sub.2 F and F.sub.2 MeSiCH:CHSiMeF.sub.2.
The prior art has attempted to provide insulating layers of silicon dioxide and fluorinated silicon dioxide from various precursors or sources which under appropriate conditions decompose to provide such layers. However, the prior art processes suffer from difficult handling of precursors, lack of volatility of sources or precursors, safety, as well as an inability to adjust the fluorine level in silicon oxide layers to provide the appropriate fluorine content in such fluorinated silicon oxide layers. These and other problems in the prior art are overcome by the present invention, as will be set forth in greater detail below.